1. Field of the Invention
The invention relates to an optical film, a light source module, and a display. More particularly, the invention relates to a beam splitting film, a backlight module, and a stereo display apparatus.
2. Description of Related Art
With development of display technology, displays having better image quality, richer color performance, and better performance effect are continuously developed. In recent years, a stereo display technology has extended to home display applications from cinema applications. Since a key technique of the stereo display technology is to ensure a left eye and a right eye of a user to respectively view left-eye images and right-eye images of different viewing angles, according to the conventional stereo display technology, the user generally wears a special pair of glasses to filter the left-eye images and the right-eye images.
However, to wear the special pair of glasses may generally cause a lot of inconveniences, especially for a nearsighted or farsighted user who has to wear a pair of glasses with corrected vision, and the extra pair of special glasses may cause discomfort and inconvenience. Therefore, a naked-eye stereo display technology becomes one of the key focuses in researches and developments. However, according to the current naked-eye stereo display technology, only one vision zone may be generated, and such vision zone is generally located at a center of a display. When the user lefts the vision zone, the user may not view the stereo image. Therefore, according to such stereo display technology, multiple users may not simultaneously view the stereo images.
Taiwan Patent No. 475334 discloses a dichroic layer, wherein an upper surface of the dichroic layer has a two-dimensional micro lens array, and a lower surface of the dichroic layer has a grating structure. Moreover, U.S. Pat. No. 7,303,323 discloses a prism, wherein a lower surface of the prism has a prism structure, and a hypotenuse of the prism is a circular arc. Moreover, Taiwan Patent No. M294667 and U.S. Pat. No. 7,529,048 disclose an optical film having a base film and prisms, wherein hypotenuse slopes of an upper prism and a lower prism are different, and the hypotenuse slope of the lower prism is less than the hypotenuse slope of the upper prism. U.S. Patent publication No. 20060209428 discloses an optical film structure having micro lenses and prisms, wherein the micro lenses are one-by-one corresponding to the prisms.